Method of bracing tubes internally for specific use in constructing aluminum or magnesium ladders



July 18, 195 g EE 2516,020

LADDERS 2 Sheets-Sheet 1 A. O. R D THOD BRACING TUBES I RNALLY FOR SPECIFIC USE IN C TRUCTING ALUMIN 0R MAGNESIUM Filed Dec. 20, 1946 INVENTOR.

' flm'i/Q Re 6 a ATTCI R N EYE July 18, 1950 REED 2,516,020

A. 0. METHOD BRACING TUBES I RNALLY F0 PECIFIC USE IN C0 TRUCTING ALUMIN OR MAGNES LADDERS Filed Dec. 20, 1946 2 Sheets-Sheet 2 Patented July 18, l950 2.2:,

H 2,516,020. I .M'ETHonJ or BRACING TUBES INTERNALLY For; 'sPEoIFIo USE IN GONSTRUCTING ALUMINUM on MAGN SIUMLA DE This invention relates to 'a rnethod orniethods for strengthening any tubular structural embers and applies specifically to membersfmade from aluminum or magnesium, commonly referredto as aluminum or magnesium tubing.

- An object of this invention is fto provid fa method of strengthening tubular members so that such members may be used to form ladders, flag poles, gang planks, scaffolding and similar types of structures involving the use of tubular members.

The tube is recognized in structural work as the strongest unit per pound of Weight that can be used, and is used in the construction of assemblies subject to tremendous stresses such as airplane engine mounts and the articles tested above, and it is believed that the internal bracing embodying the invention will make possible the construction of such assemblies with tubular members of small diameter, but equal to or possessing greater strength than members of greater diameters.

Another object of the invention is to provide a method of strengthening tubular members, that is simple and economical to use and will produce an article far superior to those being used at the present time.

With the above and other objects and advantages in view, the invention consists of the novel details of construction more fully hereinafter described, claimed and illustrated in the accompanying drawings in which:

Figure 1 is a perspective view of one form of internal bracing, embodying the invention;

Figure 2 is a transverse view of another form of internal bracing;

Figure 3 is another form of internal bracing;

Figure 4 is the same;

Figure 5 is the same;

Figure 6 is the same;

Figure 7 is a perspective view of an internal bracing member and Figure 8 is a view of an additional form of internal bracing.

Referring in detail, and more particularly to the tubular member shown, in all forms of the invention which, being of similar construction in all cases, will be designated by the numeral l 0.

In Figure 1 the member II] which is formed of aluminum or magnesium is of conventional structure, and the invention comprises the method of internally bracing this member to provide a light structure that will be equal in strength to structures made of heavy materials, such as steel and [,'i claim." (01. 29-455) m 'br'ab'in strips nor material, similar to thematerial'of which the member i0 is made, arebent along their medial line l2 to form inclined portions 13 of similar area. The strips are then placed as shown in Figurel with'the fasteners l3f in face to iace engagement with each other, and the ends are flanged asfat 'l 4. The strips ja're then placed in the member 'I ii, and means are's'ecured' as a unit by welding, riveting or shrink fitting, by utilizing temperature differential between the parts. Arc welding, spot welding, high frequency welding or other methods depending on the material, may be used.

In Figure 2, the strips [5 have a greater curved central portion I6 with straight portions I1 at each end, and whensecured with the member ID, the ends are bent to form flanges l8.

In Figure 3, the strips 19 are similar to the strips l5, except that the curved central portions 20 comprise one third of a circle, and the portions 2| are inclined with relation to the portions 20, and the ends of the portions 2| are flanged at 22. Within the circle formed b the portions 20, similar shaped portions l9 are placed, and these strips have central portions 20', inclined portions 2! and flanged ends 22'.

In Figure 4, the strips 23 have straight portions 24 and inclined portions 25 with flanged ends 26, and the portions 24, when positioned in the member I0, form a triangle.

In Figure 5, the strips 21 assume a triangular shape having three equal sides 28, and the corners of the equilateral triangle are flattened at 29 where they engage the member I0, and the strip 21' is formed similar to the strip 21, having sides 28 of equal length and flattened corners 29, but the triangle formed is of a size to fit within the triangle formed by the portions 28.

In Figure 6, strips l9 and 21 are used to form the internal bracing.

In Figure 8, the strips 30 assume a V-shape having sides 3| having flanged ends 32, and the flanged ends in all instances extend in opposite directions from each other to form contact between the strips and member Ill.

In Figure 7, a typical strip of metal is shown, which is similar to all strips previously described, but for purposes Of illustration, will be designated as 33. Triangular sections 3d are cut from the strips to lighten the weight thereof, and then the sections cut out of the strip form vertical braces 35, horizontal braces 36 and diagonal braces 31. This lightness of weight is achieved without sacrificing strength.

iron or similar materials. In this form of internal This method of stress distribution by internal bracing will greatly increase the rigidity of tubular structural members, and will permit smaller diameters and thinner walls of the tubular members with the same or greater strength as unbraced tubes of greater diameter or greater wall thickness or both.

The tubular members can be aluminum, steel, wood, concrete, magnesium, glass, tin, copper, brass or paper, and as formed, each member will sustain a greater bending stress per pound of weight than other types now in use at the present time. 1

Thus members braced by any one 0.1% the. forms previously described will support loadswhieh, at. present, are applied to tubular members of greater diameter of heavier walls or both.

It is believed that from the foregoing, descripetion, the method involving the invention will be clear to those skilled in the art, and it is: to be understood that changes may be made in the metberis used,v provided. such changes; fallw-ithi-nthe spirit of the invention and the-scope oi the mended: c aim.

Having thus; described the invention, what is claimed as new-anddesired to be secured by Let-- tersPatent is .-A methecl of making astructural unitcompris-t ing'bending strips; of suitable metal to form equilateral triangles of different sizes, the apices of the triangles being flattened to form binding surfaces, heating the larger triangle, inserting the smaller triangle within the larger triangle such that the flattened apices of said smaller triangle are located midway the sides of the larger triangle, allowing the larger triangle to cool and contract thereby resulting in a. shrink fit between the triangles, heating a tubular member, inserting the joined triangles within the tubular memher and allowing said tubular member to cool and contract thereby resulting in a shrink fit between 'thetubul-ar member. and the larger triangle.

ANCIL O. REED.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

